Semiconductor Device Including a Phase Change Material

ABSTRACT

A semiconductor device includes a transistor having a plurality of transistor cells in a semiconductor body. Each transistor cell includes a control terminal and first and second load terminals. The transistor further includes a phase change material exhibiting a solid-solid phase change at a phase transition temperature T c  between 150° C. and 400° C. The control terminals of the plurality of transistor cells are electrically connected to one another.

BACKGROUND

In semiconductor power devices such as insulated-gate bipolartransistors (IGBTs), diodes, and power field effective transistors(power-FETs) current filaments may occur in forward and reverseoperation modes, in e.g. surge current mode or blocking mode as well asduring switching of the power semiconductor device. The currentfilaments may cause hotspots that may lead to destruction of thesemiconductor power device under extreme operation conditions, e.g.operation conditions out of specification.

Therefore, it is desirable to improve heat dissipation caused by currentfilaments in semiconductor power devices.

SUMMARY

According to an embodiment of a semiconductor device, the semiconductordevice includes a transistor including a plurality of transistor cellsin a semiconductor body. Each transistor cell includes a controlterminal and first and second load terminals. The semiconductor devicefurther includes a first electrical connection electrically connectingthe first load terminals. The semiconductor device further includes asecond electrical connection electrically connecting the second loadterminals. The transistor further includes a phase change materialexhibiting a solid-solid phase change at a phase transition temperatureT_(c) between 150° C. and 400° C.

According to another embodiment of a semiconductor device, thesemiconductor device includes a diode. The diode includes an anodeterminal and a cathode terminal. The semiconductor device furtherincludes a phase change material being a constituent part of the diodebetween the anode terminal and the cathode terminal.

According to an embodiment of a semiconductor power transistor, thesemiconductor power transistor includes a plurality of transistor cellsin a semiconductor body. Each transistor cell includes a controlterminal and first and second load terminals. The semiconductor powertransistor further includes a first electrical connection electricallyconnecting the first load terminals. The semiconductor power transistorfurther includes a second electrical connection electrically connectingthe second load terminals. The semiconductor power transistor furtherincludes a phase change material exhibiting a solid-solid phase changeat a phase transition temperature T_(c) between 150° C. and 400° C. Thephase change material is part of an electrical connection from a gateterminal to a gate electrode of the semiconductor power transistor.

Those skilled in the art will recognize additional features andadvantages upon reading the following description, and upon viewing theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the present invention and are incorporated in andconstitute a part of the specification. The drawings illustrateembodiments of the present invention and together with the descriptionthe intended advantages will be readily appreciated as they becomebetter understood by reference to the following detailed description.The elements of the drawings are not necessarily to scale relative toeach other. Like reference numerals designate corresponding similarparts.

FIG. 1A illustrates one embodiment of an equivalent circuit of atransistor including a plurality of transistor cells and a phase changematerial.

FIG. 1B illustrates one embodiment of an equivalent circuit of a part ofan electrical connection of a semiconductor device including a phasechange material.

FIG. 1C to FIG. 1G illustrates cross-sectional views of embodiments of atrench gate transistor cell including a phase change material.

FIG. 2 illustrates a simplified schematic cross-sectional view of oneembodiment of a semiconductor body and a wiring area.

FIG. 3A illustrates a top view on two transistor cells covered by acontinuous layer of a phase change material.

FIG. 3B illustrates a top view of a plurality of transistor cells, eachtransistor cell including a distinct part of a phase change material.

FIG. 4 illustrates a cross-sectional view of one embodiment of a diodeincluding a phase change material as constituent part of an electricalconnection of the diode.

DETAILED DESCRIPTION

In the following detailed description reference is made to theaccompanying drawings, which form a part hereof, and in which are shownby way of illustration specific embodiments in which the invention maybe practiced. It is to be understood that other embodiments may beutilized and structural or logical changes may be made without departingfrom the scope of the present invention. For example featuresillustrated or described for one embodiment can be used on or inconjunction with other embodiments to yield yet a further embodiment. Itis intended that the present invention includes such modifications andvariations. The examples are described using specific language, whichshould not be construed as limiting the scope of the appending claim.The drawings are not scaled and are for illustrative purposes only. Forclarity, corresponding elements have been designated by the samereferences in the different drawings if not stated otherwise.

The terms “having”, “containing”, “including”, “comprising” and the likeare open and the terms indicate the presence of stated structures,elements or features but not preclude additional elements or features.The articles “a”, “an” and “the” are intended to include the plural aswell as the singular, unless the context clearly indicates otherwise.

The Figures illustrate relative doping concentrations by indicating “−”or “+” next to the doping type “n” or “p”. For example, “n” means adoping concentration which is lower than the doping concentration of an“n”-doping region while an “n⁺”-doping region has a higher dopingconcentration than an “n”-doping region. Doping regions of the samerelative doping concentration do not necessarily have the same absolutedoping concentration. For example, two different “n”-doping regions mayhave the same or different absolute doping concentrations.

The term “electrically connected” describes a permanent low-ohmicconnection between electrically connected elements, for example a directcontact between the concerned elements or a low-ohmic connection via ametal and/or highly doped semiconductor.

The term “electrically coupled” includes that one or more interveningelement(s) adapted for signal transmission may be provided between theelectrically coupled elements, for example elements that arecontrollable to temporarily provide a low-ohmic connection in a firststate and a high-ohmic electric decoupling in a second state.

FIG. 1A illustrates an equivalent circuit diagram of a semiconductordevice 100 including a transistor 110. According to one embodiment, thetransistor 110 is a field effective transistor (FET), e.g. a lateral orvertical FET. According to another embodiment the transistor 100 is ainsulated gate bipolar transistor (IGBT). The semiconductor device mayalso be a superjunction device including alternating p-doped and n-dopedregions, e.g. columns. According to one embodiment, the semiconductordevice is a discrete semiconductor device. According to anotherembodiment, the semiconductor device is an integrated circuit includingthe transistor 110 and further circuit elements, e.g. furthertransistors such as FETs, bipolar transistors, resistors, capacitors,and other active or passive circuit elements.

The transistor 110 includes a plurality of transistor cells 120 a to 120n in a semiconductor body. According to one embodiment, the number oftransistor cells connected in parallel may range between 10 and 10000.According to one embodiment, the number of transistor cells may bechosen with respect to a desired on-state resistance of a semiconductorpower transistor. According to one embodiment, the transistor is one ofa power FET and a power IGBT configured to conduct currents of more than1 A between first and second load terminals. The transistor 110 mayinclude a superjunction structure.

The semiconductor body may include a semiconductor substrate, e.g. asilicon (Si) substrate, a silicon carbide (SiC) substrate, a galliumnitride (GaN) substrate or another single semiconductor or compoundsemiconductor substrate. Furthermore, one or more optional semiconductorlayer(s), e.g. epitaxial semiconductor layers, may be formed on thesemiconductor substrate. According to one embodiment, the semiconductorbody includes a wide bandgap material with a bandgap greater than 1.7eV. The wide bandgap material my be one of gallium phosphide (GaP),gallium nitride (GaN) and silicon carbide (SiC), for example. Accordingto another embodiment, the semiconductor body is a thin siliconsubstrate, i.e. a silicon substrate having a thickness less than 80 μm,or less than 50 μm that may be manufactured by removing substratematerial from a front and/or rear side from a base substrate.

In one embodiment, the transistor 110 is a power transistor and thesemiconductor device 100 is a discrete semiconductor device or anintegrated circuit. The transistor cells 120 a to 120 n may be one ofbipolar NPN transistor, bipolar PNP transistors, n-channel FETs,p-channel FETs, IGBTs.

Each of the transistor cells 120 a to 120 n includes a first loadterminal 121, a second load terminal 122 and a control terminal 123.According to one embodiment the transistor cells 120 a to 120 n areadapted to conduct currents of more than 1 A between the first loadterminal 121 and the second load terminal 122.

In case of a bipolar transistor, the first load terminal 121 may be acollector terminal, the second load terminal 122 may be an emitterterminal, and the control terminal 123 may be a base terminal. Theallocation of the first and second load terminals 121, 122 may beinterchanged with respect to the above allocation. In other words, thefirst load terminal 121 may be the collector and the second loadterminal 122 may be the emitter.

In case of a FET, the first terminal 121 may be a source terminal, thesecond load terminal 122 may be a drain terminal and the controlterminal 123 may be a gate terminal. The allocation of the first and thesecond load terminals 121, 122 may be interchanged with respect to theabove allocation. In other words, the first load terminal 121 may be thedrain terminal and the second load terminal 121 may be the sourceterminal.

In case of an IGBT, the first load terminal 121 may be a collectorterminal, the second load terminal 122 may be an emitter terminal, andthe control terminal 123 may be a gate terminal. The allocation of thefirst and second load terminals 121, 122 may be interchanged withrespect to the above allocation. In other words, the first load terminal121 may be the collector and the second load terminal 122 may be theemitter.

The first load terminals 121 a to 121 n are electrically connected via afirst electrical connection 140 to a transistor cell array sourceterminal 150, e.g. a source bond pad or a contact area of a source line.The second load terminals 122 a to 122 n are electrically connected viaa second electrical connection 145 to a transistor cell array drainterminal 155, e.g. a drain bond pad or a contact area of a drain line.The control terminals 123 a to 123 n are electrically connected via agate line 165 to a transistor cell array gate terminal 160, e.g. a gatebond pad or a contact area of the gate line.

The electrical connections 140, 145 and the gate line 165 may includelow-ohmic materials, e.g. one, a plurality of or any combination of ametal, a metal alloy and a highly doped semiconductor. According to oneembodiment, the electrical connections are part of one or more wiringlayer(s) and interconnection elements between the wiring layers, e.g.vias. According to one embodiment, the gate line 165 includes dopedpolysilicon gate line material.

In case of a discrete semiconductor device, the transistor cell arraysource terminal 150, the transistor cell array drain terminal 155, andthe transistor cell array gate terminal 160 may be bond pads.

In case of an integrated circuit, at least one of the transistor cellarray source terminal 150, the transistor cell array drain terminal 155and the transistor cell array gate terminal 160 is electrically coupledto another circuit element of the semiconductor device, i.e. to anothercircuit element integrated in the semiconductor body. According to oneembodiment, the transistor cell array gate terminal 160 is electricallycoupled to a gate driver circuit integrated in the semiconductor body.

The transistor 110 includes a phase change material (PCM) illustrated inthe equivalent circuit diagram of FIG. 1A by simplified elements 130 a .. . 130 f. The transistor 110 may include one, any combination of or allof PCM elements 130 a . . . 130 f. The PCM may be in contact with orform part of the first electrical connection 140 from the transistorcell array source terminal 150 to one or several or all of the firstload terminals 121 a . . . 121 n. According to one embodiment, the PCMis in contact with or forms part of elements 130 b of the firstelectrical connection 140 that are separate for each of the first loadterminals 121 a . . . 121 n. In other words, each transistor cellincludes a separate portion of PCM that is in contact with or forms partof a respective part of the first electrical connection 140 which islocated between a respective one of the first load terminals 121 a . . .121 n and a part of the first electrical connection 140 that is sharedbetween all of the first load terminals 121 a . . . 121 n. In additionor alternatively, the PCM is in contact with or forms part of element130 a of the first electrical connection 140 that is common for each ofthe first load terminals 121 a . . . 121 n.

In addition or alternatively, the PCM may be in contact with or formpart of the second electrical connection 145 from the transistor cellarray drain terminal 155 to one or several or all of the second loadterminals 122 a . . . 122 n. According to one embodiment, the PCM is incontact with or forms part of elements 130 d of the second electricalconnection 145 that are separate for each of the second load terminals122 a . . . 122 n. In other words, each transistor cell includes aseparate portion of PCM that is in contact with or forms part of arespective part of the second electrical connection 145 which is locatedbetween a respective one of the second load terminals 122 a . . . 122 nand a part of the second electrical connection 145 that is sharedbetween all of the second load terminals 122 a . . . 122 n. In additionor alternatively, the PCM is in contact with or forms part of element130 c of the second electrical connection 145 that is common for each ofthe second load terminals 122 a . . . 122 n.

In addition or alternatively, the PCM may be in contact with or formpart of the gate line 165 from the transistor cell array gate terminal160 to one or several or all of the control terminals 123 a . . . 123 n.According to one embodiment, the PCM is in contact with or forms part ofelements 130 f of the gate line 165 that are separate for each of thecontrol terminals 123 a . . . 123 n. In other words, each transistorcell includes a separate portion of PCM that is in contact with or formspart of a respective part of the gate line 165 which is located betweena respective one of the control terminals 123 a . . . 123 n and a partof the gate line 165 that is shared between all of the control terminals123 a . . . 123 n. In addition or alternatively, the PCM is in contactwith or forms part of element 130 e of the gate line 165 that is commonfor each of the control terminals 123 a . . . 123 n.

According to one embodiment, the PCM is arranged at a chip front side,e.g. on or below a chip wiring layer, in contact with a surface of thesemiconductor body and/or on dielectric layers adjoining the surface ofthe semiconductor body. In addition or as an alternative, the PCM may beformed at a rear side of a chip, e.g. in the form of distinct partsand/or as a continuous area covering multiple transistor cells. As anexample, the PCM may be part of a wiring, e.g. metal layer stack at therear side.

The PCM exhibits a solid-solid phase change at a phase transitiontemperature T_(c) between 150° C. and 400° C., or between 200° C. and300° C. According to one embodiment the PCM is crystalline below thephase transition temperature T_(c) and is amorphous above the phasetransition temperature T_(c).

The PCM may be disposed in crystalline form locally or large-area inregions of the semiconductor device 100 carrying high current densitiesand high thermal loads during operation. Such regions may be regions ofhigh thermal load during switching or regions of high electric fields,e.g. source regions or emitter regions or edge regions of IGBTs, diodes,power-FETs, regions of early avalanche breakdown or latch-up, e.g.regions including break-over diodes which result in locally andwell-reduced breakdown voltage of the device, deep trenches, and regionsincluding amplifying gate structures of thyristors. The PCM may also bedisposed in an area of the gate, e.g. gate connection. In this case, atemperature induced increase of a resistivity of the PCM results in awell-controlled turn off of individual gates due locally increasedtemperatures, e.g. due to current filaments.

During a short and intensive current pulse in these regions, the PCMexhibits a solid-solid phase transition at the phase change temperatureT_(c) within a short time period, e.g. within a typical period between50 ns to 200 ns and absorbs latent heat while remaining at the phasechange temperature T_(c). In other words, the PCM acts as a heat sinkand heat can effectively be dissipated by the PCM. This behaviorcounteracts occurrence of high temperatures in regions of thesemiconductor device 100 in which the PCM is disposed and thereforecounteracts hot spot generation and damage in these regions of thesemiconductor device 100.

The phase transition temperature T_(c) and the latent heat that isabsorbed by the PCM may be adjusted by selecting the PCM or acombination of phase change materials accordingly. An amount of latentheat absorbed by the PCM may be adjusted by dimensions of PCM that ispresent locally. A thickness of the PCM may be adjusted with respect toan optimal combination of latent heat, local heat dissipation, andelectrical conductivity.

There exist a broad range of PCMs, e.g. salts (e.g. M_(n)H₂O), organicPCMs (e.g. C_(n)H_(2N+2)), and eutectic compounds of PCMs that havecharacteristic phase transition temperatures T_(C) and latent heats.According to one embodiment, the PCM includes a chalcogenide, e.g.GeSbTe (Germanium-Antimony-Tellurium or GST).

The PCM, e.g. GeSbTe, may be doped with one or a combination of carbon(C), nitride (N), oxygen (O), or indium (In) for adjusting the phasetransition temperature T_(c). A dopant concentration of C and N rangestypically between 2% and 10% and the phase transition temperature T_(c)tends to raise with raising dopant concentration. Thereby, the phasetransition temperature may be adjusted between 200° C. and 300° C., forexample.

A short current pulse of high amplitude as caused by e.g. a shortcircuit or by a cosmic radiation event can effect the phase change fromthe crystalline to the amorphous phase. A specific resistivity of thePCM in the amorphous phase is considerably higher than in thecrystalline phase. Thus, the phase change causes a voltage drop due toincrease of resistivity that counteracts the formation of currentfilaments and results decomposition of current filaments. Theresistivity of the PCM may range between 10⁻⁴ Ωcm to 10⁻² Ωcm in thecrystalline phase, i.e. be low-ohmic and range between 1 Ωcm to 10³ Ωcmin the amorphous phase.

The phase change of the PCM is reversible and amorphous parts of the PCMmay be converted into crystalline form by an appropriate process, e.g.by annealing. Annealing may be achieved by a moderate current appliedover an extended time period that heats the amorphous material over thecrystallization temperature and keeps the amorphous material at thistemperature until nucleation begins and the material startsrecrystallization. Annealing may be carried out during normal operationof the semiconductor device 100.

FIG. 1B illustrates one example of an equivalent circuit of any of theequivalent circuit elements 130 a . . . 130 f including PCM. Theequivalent circuit elements 130 a . . . 130 f denote a part of theelectrical connection from one of the transistor cells 120 a to 120 n toone of the transistor cell array source terminal 150, the transistorcell array drain terminal 155, and the transistor cell array gateterminal 160. The equivalent circuit elements 130 a . . . 130 f includea first resistor element 131 that is connected in series with a secondresistor element 132 and a third resistor element 133, the secondresistor element 132 and the third resistor element being connected inparallel.

According to one embodiment, the PCM may be part of or correspond to thefirst resistor 131 and may therefore be serially connected to one orseveral or all of the transistor cells 120 a to 120 n and one of thetransistor cell array source terminal 150, the transistor cell arraydrain terminal 155, and the transistor cell array gate terminal 160. Theresistors 132, 133 may include low-ohmic materials such as metal orhighly doped semiconductor material, e.g. polysilicon, or a combinationthereof. The resistors 132, 133 may also be combined. According toanother example, one or both of resistors may include PCM and alow-ohmic material, e.g. metal and/or doped semiconductor material.

According to another embodiment, the PCM may be part of or correspond tothe second resistor 132 and/or third resistor 133. The PCM may then beconnected in series with a low-ohmic first resistor, e.g. a metal or ahighly doped semiconductor.

FIG. 1C illustrates a cross-sectional view of one embodiment of thetransistor cells 120. In the illustrated embodiment, the transistor cell120 is a trench gate transistor cell.

According to one embodiment, the semiconductor body 105 includes ap-doped body region 124 and an n-doped region 172, e.g. an n-doped driftzone electrically connected to the second load terminal 122 of thetransistor cell 120. At a first surface 175 of the semiconductor body105 a trench 176 extends through the body region 124 into the n-dopedregion 172. The trench includes a gate electrode 173 that iselectrically connected to or forms part of the control terminal 123 ofthe transistor cell 120 and is electrically isolated from a surroundingpart of the semiconductor body 105 by a dielectric structure 125. Ann⁺-doped source region that is electrically connected to or forms partof the first load terminal 121 of the transistor cell 120 adjoinssidewalls of the trench 176 at the first surface 175 of thesemiconductor body 105.

A PCM 135 a is disposed on the trench 176. The PCM 135 a is inmechanical and electrical contact with the gate electrode 173. The PCM135 a induces a higher voltage drop after the phase transition at hightemperatures. This higher voltage drop results in a lower voltageapplied to the gate and, consequently in a self-controlled turn-off ofthe device regions or transistor cells that undergo a criticaltemperature. The PCM 135 a counteracts hot spot generation and currentfilaments by acting as a heat sink when undergoing a phase transition.According to other embodiments, the PCM 135 a may also be disposedinside the trench 176 (c.f. FIGS. 1D and 1E).

Referring to the schematic cross-sectional view of FIG. 1F, a PCM 135 bmay also be disposed at a second surface 178 opposite to the firstsurface 175, e.g. at a rear side such as a drain terminal of an FET or acollector terminal of an IGBT. The PCM 135 b may include distinct parts,e.g. covering one or even a plurality of transistor cells. The PCM 135 bmay also be large-area or extend over an overall surface of thesemiconductor body 105. A contact region 179, e.g. a highly n⁺-dopedregion and/or a metal layer or metal layer stack may be interposedbetween the n-doped region 172, e.g. drift zone and the PCM 135 b (c.f.FIG. 1F). During a current pulse of high amplitude the PCM 135 bcounteracts hotspot formation and current filaments in the transistorcell array.

A PCM 135 c may also be disposed on the n⁺-doped source region 171, e.g.with an intermediate contact region 177 (c.f. FIG. 1G). During a currentpulse of high amplitude the PCM 135 c counteracts hotspot formation andcurrent filaments in the transistor cell array. The PCM 135 c mayinclude distinct parts, e.g. covering one or even a plurality oftransistor cells. The PCM 135 c may also be large-area or extend over anoverall surface of the semiconductor body 105. The same principle can beapplied to insulated gate bipolar transistors (IGBTs). In this case, ap-doped emitter is formed between a rear side metallization and a driftzone. Optionally, a field stop zone is formed between the drift zone andthe p-doped emitter.

FIG. 2 illustrates a simplified cross-sectional view of a semiconductorbody 205. According to one embodiment, the semiconductor body 205includes as a portion or corresponds to the semiconductor body 105 asdescribed with reference to FIGS. 1A to 1C. According to anotherembodiment the semiconductor body 205 includes a diode.

A rear side of the semiconductor body 205 is in contact with a rear sidecontact 270, e.g. a metal layer or a metal layer stack and a wiringlayer 275 is disposed on a front side of the semiconductor body 205. Thesemiconductor body 205 includes a PCM 236 a which is illustrated in asimplified manner by a line. The PCM 236 a may be disposed in any partof the semiconductor body 205 where highest current pulses may appear,e.g. inside a gate trench as part of a gate line (c.f. FIGS. 1D, 1E).The PCM 236 a may extend into the semiconductor body 205 from the frontside or from the rear side. A PCM 236 b may also be disposed locally orlarge-area in an area of the wiring layer 275, e.g. as part or incontact with a metallization layer, via, interlayer contact line orcontact plug (c.f. FIGS. 1C, 1F, 1G). The PCM 236 b may include distinctparts, e.g. covering one or even a plurality of transistor cells. ThePCM 236 b may also be large-area or extend over an overall surface ofthe semiconductor body 205. In FIG. 2, the PCM 236 b is illustrated in asimplified manner by a line. A PCM 236 c may also be disposed locally orlarge-area in an area of the rear side contact 270, e.g. as part or incontact with a metallization layer or metallization layer stack. The PCM236 c may include distinct parts, e.g. covering one or even a pluralityof transistor cells. The PCM 236 c may also be large-area or extendedover an overall surface of the semiconductor body 205. In FIG. 2, thePCM 236 c is illustrated in a simplified manner by a line.

The semiconductor body 205 may include edge regions surrounding oradjoining a central region as illustrated by lines BB′ and CC′ of FIG.2. As an example, the edge region may be an edge termination areaincluding edge termination structures, e.g. guard rings, field plates,Junction termination extension (JTE). The central region may include atransistor cell area or an active diode area, for example. The PCMs 236a . . . 236 c may be disposed in or extend into the edge regions of thesemiconductor body 205 to prevent damage to the semiconductor device,e.g. by high-amplitude current pulses in the edge regions.

In regards to the details of the PCMs 236 a . . . 236 c, such ascharacterizing parameters or materials, reference is taken to theembodiments illustrated in FIGS. 1A to 1G and the related part of thedescription above.

FIG. 3A illustrates one example of a top view of the semiconductor body105 covered by a PCM 3390. According to the illustrated part of theembodiment, the semiconductor body 105 includes transistor cells 120 aand 120 b of a transistor cell array, e.g. FET cell array or IGBT cellarray. A continuous part of the PCM 3390 has an area that issufficiently large to cover a surface area of the two transistor cells120 a and 120 b. According to an embodiment, the area of the PCM 3390ranges between 10⁻³ mm² to 1 mm² or typically between 5×10⁻³ mm² and10⁻¹ mm².

FIG. 3B illustrates another example of a top view of the semiconductorbody 105. According to the illustrated part of the embodiment, thesemiconductor body 105 includes transistor cells 120 a to 120 d of atransistor cell array, e.g. FET cell array or IGBT cell array. Each ofthe transistor cells 120 a to 120 d includes distinct parts 3391 a to3391 d of PCM. The distinct parts 3391 a to 3391 d of the PCM may bedisposed in any parts of the transistor cells 120 a to 120 n, e.g. inone or in a combination of the semiconductor body, at a front side, e.g.in a wiring area, at a rear side, e.g. as part of a rear side contact.

In regards to further features of the PCM 3390 and the parts 3391 a to3391 d, such as characterizing parameters or materials, reference istaken to the embodiments illustrated in FIGS. 1A to 1G and the relatedpart of the description above.

FIG. 4 illustrates a semiconductor device 400 that includes a diode in asemiconductor body 405 and further includes a PCM. The semiconductorbody 405 may include a semiconductor substrate, e.g. a silicon (Si)substrate, a silicon carbide (SiC) substrate or another semiconductor orsemiconductor compound substrate and one or more optional semiconductorlayers thereon.

At a first surface 475, e.g. a front side of the semiconductor body 405,a p-doped anode region 480 is formed. The p-doped anode region 480 issurrounded by an n-doped drift region 401 which adjoins an n⁺-dopedcathode region 485 at a second surface 478, e.g. a rear side. The anoderegion 480 is electrically coupled to an anode terminal 490, e.g. acontact area or bond pad. The cathode region 485 is electrically coupledto a cathode terminal 495, e.g. a rear side metallization layer ormetallization layer stack.

Between the anode region 480 and the anode terminal 490 and/or betweenthe cathode region 485 and the cathode terminal 495, a PCM 430 a, 430 bis disposed. Similar to the embodiments illustrated in FIGS. 1A to 2,the PCM 430 a may be in contact with or part of the electricalconnection from the anode region 480 to the anode terminal 490, e.g. aspart of an wiring area and the PCM 430 b may be in contact with or partof the electrical connection from the cathode region 485 to the cathodeterminal 495, e.g. as part of a rear side contact.

In regards to further features of the PCM 430 a, 430 b of thesemiconductor device 400, such as characterizing parameters ormaterials, reference is taken to the embodiments illustrated in FIGS. 1Ato 1G and the related part of the description above.

In the context of the present specification, the term “metal” should beunderstood as including the more general term conductor. For example,the material of a electrode has not necessarily to be made out of metalbut can also be made of any conducting material like e.g. asemiconductor layer of a metal-semiconductor compound of any othersuitable material.

Further, terms such as “first”, “second”, and the like, are also used todescribe various elements, regions, sections, etc. and are also notintended to be limiting. Like terms refer to like elements throughoutthe description.

It is to be understood that the features of the various embodimentsdescribed herein may be combined with each other, unless specificallynoted otherwise.

Although specific embodiments have been illustrated and describedherein, it will be appreciated by those of ordinary skill in the artthat a variety of alternate and/or equivalent implementations may besubstituted for the specific embodiments shown and described withoutdeparting from the scope of the present invention. This application isintended to cover any adaptations or variations of the specificembodiments discussed herein. Therefore, it is intended that thisinvention be limited only by the claims and the equivalents thereof.

What is claimed is:
 1. A semiconductor device, comprising: a transistor,including a plurality of transistor cells in a semiconductor body, eachtransistor cell including a control terminal and first and second loadterminals; wherein the transistor further includes a phase changematerial exhibiting a solid-solid phase change at a phase transitiontemperature T_(c) between 150° C. and 400° C.; and wherein the controlterminals of the plurality of transistor cells are electricallyconnected to one another.
 2. The semiconductor device of claim 1,wherein the semiconductor body includes one of silicon and a widebandgap material with a bandgap greater than 1.7 eV.
 3. Thesemiconductor device of claim 1, wherein the phase change of the phasechange material is from a crystalline phase below T_(c) to an amorphousphase above T_(c).
 4. The semiconductor device of claim 3, wherein thephase change material includes a chalcogenide.
 5. The semiconductordevice of claim 4, wherein the phase change material includes GeSbTe. 6.The semiconductor device of claim 1, wherein the phase change materialis doped with at least one of C, N, O, and In.
 7. The semiconductordevice of claim 1, wherein the phase transition temperature T_(c) isbetween 200° C. and 300° C.
 8. The semiconductor device of claim 1,wherein the phase change material is part of at least one of anelectrical connection from a transistor cell array source terminal tothe first load terminal, an electrical connection from a transistor cellarray gate terminal to the control terminal and an electrical connectionfrom a transistor cell array drain terminal to the second load terminal.9. The semiconductor device of claim 8, wherein the phase changematerial is electrically connected to a polysilicon gate line material.10. The semiconductor device of claim 1, wherein the phase changematerial includes at least one continuous part congruent with a surfacearea of at least two of the plurality of transistor cells.
 11. Thesemiconductor device of claim 1, wherein a rear side of thesemiconductor body is mounted on a lead frame, and wherein the phasechange material adjoins at least one of a front side wiring layer and arear side contact material electrically coupling the semiconductor bodyto the lead frame.
 12. The semiconductor device of claim 1, wherein thephase change material is located in an edge region of the transistor.13. The semiconductor device of claim 1, wherein each one of theplurality of transistor cells includes a distinct part of the phasechange material.
 14. The semiconductor device of claim 1, wherein thesemiconductor device is one of a power FET and a power IGBT configuredto conduct currents of more than 1 A between the first and second loadterminals.
 15. A semiconductor device, comprising: a diode including ananode region at a first surface of a semiconductor body and a cathoderegion at a second surface of the semiconductor body opposite to thefirst side; an anode terminal electrically coupled to the anode region;a cathode terminal electrically coupled to the cathode region; and aphase change material being a constituent part of the diode between theanode terminal and the cathode terminal.
 16. The semiconductor device ofclaim 15, wherein the phase change material is part of at least one ofan electrical connection from an anode contact to the anode terminal andan electrical connection from a cathode contact to the cathode terminal.17. The semiconductor device of claim 15, wherein the phase changematerial includes a chalcogenide.
 18. The semiconductor device of claim15, wherein a rear side of the semiconductor body is mounted on a leadframe, and wherein the phase change material adjoins at least one of afront side wiring layer and a rear side contact material electricallycoupling the semiconductor body to the lead frame.